chore: manual translations (#42811)

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Nicholas Carrigan (he/him)
2021-07-09 21:23:54 -07:00
committed by GitHub
parent a3395269a0
commit c4fd49e5b7
806 changed files with 8935 additions and 4378 deletions

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@ -14,26 +14,42 @@ Interestingly the sum of the proper divisors of 220 is 284 and the sum of the pr
Perhaps less well known are longer chains. For example, starting with 12496, we form a chain of five numbers:
<div style="text-align: center;">
12496 → 14288 → 15472 → 14536 → 14264 (→ 12496 → ...)
</div>
$$ 12496 → 14288 → 15472 → 14536 → 14264 \\,(→ 12496 → \cdots) $$
Since this chain returns to its starting point, it is called an amicable chain.
Find the smallest member of the longest amicable chain with no element exceeding one million.
Find the smallest member of the longest amicable chain with no element exceeding `limit`.
# --hints--
`amicableChains()` should return a number.
`amicableChains(300)` should return a number.
```js
assert(typeof amicableChains() === 'number');
assert(typeof amicableChains(300) === 'number');
```
`amicableChains()` should return 14316.
`amicableChains(300)` should return `220`.
```js
assert.strictEqual(amicableChains(), 14316);
assert.strictEqual(amicableChains(300), 220);
```
`amicableChains(15000)` should return `220`.
```js
assert.strictEqual(amicableChains(15000), 220);
```
`amicableChains(100000)` should return `12496`.
```js
assert.strictEqual(amicableChains(100000), 12496);
```
`amicableChains(1000000)` should return `14316`.
```js
assert.strictEqual(amicableChains(1000000), 14316);
```
# --seed--
@ -41,16 +57,68 @@ assert.strictEqual(amicableChains(), 14316);
## --seed-contents--
```js
function amicableChains() {
function amicableChains(limit) {
return true;
}
amicableChains();
amicableChains(300);
```
# --solutions--
```js
// solution required
function amicableChains(limit) {
function getSmallestMember(chain) {
let smallest = chain[0];
for (let i = 1; i < chain.length; i++) {
if (smallest > chain[i]) {
smallest = chain[i];
}
}
return smallest;
}
function getFactorsSums(limit) {
const factorsSums = new Array(limit + 1).fill(1);
for (let i = 2; i <= limit / 2; i++) {
for (let j = 2 * i; j <= limit; j += i) {
factorsSums[j] += i;
}
}
return factorsSums;
}
const factorsSums = getFactorsSums(limit);
const checkedNumbers = new Set();
let longestChain = 0;
let smallestMember = 0;
for (let i = 0; i <= limit; i++) {
const curChain = [];
let curNumber = i;
while (!checkedNumbers.has(curNumber) && factorsSums[curNumber] <= limit) {
curNumber = factorsSums[curNumber];
const chainStart = curChain.indexOf(curNumber);
if (chainStart === -1) {
curChain.push(curNumber);
continue;
}
const chainLength = curChain.length - chainStart;
if (chainLength > longestChain) {
longestChain = chainLength;
smallestMember = getSmallestMember(curChain.slice(chainStart));
}
break;
}
for (let j = 0; j < curChain.length; j++) {
checkedNumbers.add(curChain[j]);
}
}
return smallestMember;
}
```